From 917759108c232f4ca72493325d004859cdb55855 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Mon, 9 Aug 2010 11:05:15 -0400
Subject: [git-un-diff-whitespace] Don't write out unmodified files

---
 bin/git-un-diff-whitespace | 47 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 12 deletions(-)

diff --git a/bin/git-un-diff-whitespace b/bin/git-un-diff-whitespace
index 4e71f04..5e0549d 100755
--- a/bin/git-un-diff-whitespace
+++ b/bin/git-un-diff-whitespace
@@ -8,15 +8,25 @@
 # Copyright 2010 Colin Walters <walters@verbum.org>
 # Licensed under the new-BSD license (http://www.opensource.org/licenses/bsd-license.php)
 
-import os,sys,re,subprocess
+import os,sys,re,subprocess,hashlib
 
 hunk_re = re.compile(r'^@@ -\d+,\d+ \+(\d+),(\d+) @@')
 ws_re = re.compile(r'^(.*?)[ \t]+$')
-file_re = re.compile(r'^\-\-\- b/(.+)')
+file_re = re.compile(r'^\+\+\+ b/(.+)')
+
+def hashfile(path):
+  h = hashlib.sha1()
+  f = open(path)
+  b = f.read(8192)
+  while b != '':
+    h.update(b)
+    b = f.read(8192)
+  f.close()
+  return h.hexdigest()
 
 def strip_whitespace_regions(filename, hunks):
   if len(hunks) == 0:
-    return
+    return False
   filename_t = filename + '.tmp'
   tmpf = open(filename_t, 'w')
   f = open(filename)
@@ -38,8 +48,15 @@ def strip_whitespace_regions(filename, hunks):
     i = i+1
   tmpf.close()
   f.close()
-  os.rename(filename_t, filename)
-  print "wrote " + filename
+  old = hashfile(filename)
+  new = hashfile(filename_t)
+  if old != new:
+    os.rename(filename_t, filename)
+    print "wrote " + filename
+    return True
+  else:
+    os.unlink(filename_t)
+    return False
 
 def main():
   toplevel = subprocess.Popen(['git', 'rev-parse', '--show-toplevel'], stdout=subprocess.PIPE).communicate()[0]
@@ -52,10 +69,10 @@ def main():
                                  stderr=sys.stderr)
   diff_lines = commit_proc.stdout.readlines()
   commit_proc.wait()
-  subprocess.check_call(['git', 'reset', 'HEAD^'], stdout=sys.stdout, stderr=sys.stderr)
   curfile = None
   hunks = []
   files = []
+  modified_files = []
   for line in diff_lines:
     if curfile is not None:
       match = hunk_re.match(line) 
@@ -65,16 +82,22 @@ def main():
     match = file_re.match(line)
     if match:
       filename = match.group(1)
-      strip_whitespace_regions(curfile, hunks)
+      modified = strip_whitespace_regions(curfile, hunks)
       curfile = filename
       files.append(filename)
+      if modified:
+        modified_files.append(filename)
       hunks = []
   if curfile:
-    strip_whitespace_regions(curfile, hunks)
-  add_args = ['git', 'add']
-  add_args.extend(files)
-  subprocess.check_call(add_args, stdout=sys.stdout, stderr=sys.stderr)
-  subprocess.check_call(['git', 'commit', '-c', 'ORIG_HEAD'], stdout=sys.stdout, stderr=sys.stderr)
+    modified = strip_whitespace_regions(curfile, hunks)
+    if modified:
+      modified_files.append(curfile)
+  if modified_files:
+    add_args = ['git', 'add']
+    add_args.extend(modified_files)
+    subprocess.check_call(add_args, stdout=sys.stdout, stderr=sys.stderr)
+  else:
+    print "No trailing whitespace found in HEAD"
 
 if __name__ == '__main__':
   main()
-- 
cgit